GM> GM> OTOH, I did note the following:
GM> GM> (a) the skin effect is calculated as the depth where the current
GM> GM> decreases to 1/e of the surface current, or about 36%;
GM> GM> (b) the depth of penetration varies as 1/f;
GM> GM> (c) one of their examples gives the depth of penetration in a
GM> GM> copper conductor at 100 MHz = 0.00035 inches.

GM>On re-reading the text, I found I was wrong!!!

GM>The depth varies inversely as the SQUARE ROOT of f, so if it is
GM>0.00035 at 100 MHz, it would be 0.35 at 100 Hz.

GM>Negligible at the size of most conductors I would ever use --
GM>even the cables on my arc welder are less than 1/2" diameter --
GM>but quite significant in the case of 1" diam conductors on HV
GM>transmission lines.

GM>But I'm told another reason why these conductors are made hollow
GM>is that they then have a larger surface area for dissipation of
GM>heat.

I'm a bit puzzled. How is the hollow core  going to
dissipate heat when the hollow itself traps the heat inside
itself?

Jay

GM>I'm not sure how significant this is. Possibly under fault
GM>conditions it could be very important.


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